1. Field of the Invention
The present invention relates to a disengage device and particularly, to a disengage device which is used in an automatic pilot system in an aircraft and blocks a transmission of a steering force (driving force of a control surface).
2. Description of the Related Art
Currently, an automatic pilot (autopilot) device has been put to practical use, which realizes a flight along a predetermined path by automatically driving and controlling the control surface of an aircraft. The automatic pilot system is provided with a drive unit such as a servomotor or the like for driving the control surface, and a control unit for controlling the drive unit, however, there is a case where the drive unit or the control unit fails and generates an inappropriate driving force. To handle such situation, there is proposed a “disengage device” which prevents the driving force of the drive unit from transmitting to the control surface.
As an earlier developed disengage device, as shown in FIG. 3, an electromagnetic clutch type disengage device in which an electromagnetic clutch 300 actuated by electromagnetic force is provided between a servomotor 100 as a drive unit and an output shaft 200 for transmitting the driving force from the servomotor 100 to the control surface has been proposed (for example, refer to “Aeronautical Engineering Course, Vol. 17, autopilot” by Daijiro Murayama, published by Japan Aeronautical Engineer's Association, page 83-84, Apr. 10, 1983). In this disengage device, a rotation torque (driving force) from the servomotor 100 is transmitted to the output shaft 200, whereas the transmission of the rotation torque is blocked by disengaging a friction plate of the electromagnetic clutch 300.
However, the electromagnetic clutch type disengage device utilizes electromagnetic force, so that a power supply for supplying electricity needs to be provided. Therefore, the operation may stop not only when the disengage device itself breaks down, but also when electrical supply is interrupted due to the electric system failure, thus having a relatively low reliability. Since the size and the weight of the friction plate forming the electromagnetic clutch are large, the device becomes large and the weight thereof increases.
The electromagnetic clutch type disengage device is for preventing the transmission of the rotation movement of the servomotor, so that it is not directly applied to a “manual type” control system in which the operation amount of a control stick is transmitted to the control surface by using a push-pull rod.
The electromagnetic clutch transmits the driving force irrespective to the phases of the drive side (servomotor) and the driven side (output shaft), so that a rotation position of the servomotor does not corresponds to the position of the control stick in automatic pilot in one-to-one relation. Accordingly, a device for corresponding the rotation position of the servomotor to the position of the control stick in one-to-one relation needs to be separately provided so that the control state can be recognized from the position of the control stick in automatic pilot.
An object of the present invention is to provide a disengage device which can be applied to a “manual type” control system using a push-pull rod, requiring no electricity, and has high reliability.